At present, mobile phones and other wireless communication devices come in a plurality of systems based on different standards. For example, in the Japanese mobile phone system, the PDC system, a CDMA system, a PHS system, etc. have spread.
Usually, a wireless communication device is designed for one of these standards, but the frequency band assigned to each system has become tighter along with a recent spread of mobile phones, so devices have being shifting to multi-band and multi-mode specifications.
Further, in order to supply stable, high performance service, devices are being designed for hybrid operation enabling handoff between different frequency bands, change of an operation mode (for example 1x mode and 1xEVDO), etc.
Various communication devices designed for such multi-band and multi-mode specifications are being proposed (see for example Patent Documents 1 and 2).
A dual band wireless communication device disclosed in Patent Document 1 realizes reduction of the size of the circuits. It has a first frequency conversion unit converting a transmission IF signal to a first transmission signal and converting a first reception signal to a reception IF signal and a second frequency conversion unit converting the first transmission signal to a second transmission signal and converting a second reception signal to the first reception signal and operates a switch by a control signal to switch between an 800 MHz band system using the first transmission signal and first reception signal and a 1900 MHz band system using the second transmission signal and second reception signal.
A multi-band antenna switch circuit and a communication device using same disclosed in Patent Document 2 have a first diplexer 1 having a first transmission terminal, a second reception terminal, and a first common terminal, a second diplexer 2 having a second transmission terminal, a first reception terminal, and a second common terminal, and a switch circuit having a first transmission/reception terminal, a second transmission/reception terminal, and an antenna terminal and in which either one of the first transmission/reception terminal and the second transmission/reception terminal is connected to the antenna terminal by switching, wherein the first common terminal is connected to the first transmission/reception terminal, the second common terminal is connected to the second transmission/reception terminal, and a notch filter is provided between the antenna terminal and the switch circuit.
FIG. 1 is a block diagram showing an example of the configuration of a generally known wireless communication device.
The wireless communication device of FIG. 1 is configured by an 800 MHz band CDMA system (for example ARIB STD-T53, hereinafter abbreviated as an “800 MHz band system”), a 2 GHz band system (for example ARIB STD-T64, hereinafter abbreviated as a “2 GHz band system”), and a GPS receiver.
Further, the wireless communication terminal of FIG. 1 is configured as a diversity type for both of the 800 MHz band system and 2 GHz band system in order to improve the through-put or enable a hybrid operation in data communication.
As concrete assigned frequencies, in the 800 MHz band system, the transmission frequencies are 898 to 891 MHz and 915 to 925 MHz and the reception frequencies are 843 to 846 MHz and 860 to 870 MHz, and in the 2 GHz band system, the transmission frequency is 1920 to 1980 MHz, and the reception frequency is 2110 to 2170 MHz. Further, a GPS reception frequency is 1575.42 MHz.
In FIG. 1, the 800 MHz band system includes a power amplifier 1 amplifying a transmission signal up to a predetermined level, a filter 2 for attenuating a frequency component of the 2 GHz band system, a filter 3 for attenuating a GPS reception frequency component, a duplexer 4 for demultiplexing a transmission/reception signal of the 800 MHz band, a low noise amplifier 5 amplifying a reception signal of an 800 MHz band primary receiver circuit with a low noise, a low noise amplifier 12 amplifying a reception signal of an 800 MHz band secondary receiver circuit with a low noise, and an 800 MHz band reception filter 13 for eliminating unnecessary waves.
The 2 GHz band system includes a power amplifier 6 amplifying a transmission signal up to a predetermined level, a filter 7 for attenuating a frequency component of the 800 MHz band system, a filter 8 for attenuating a GPS reception frequency component, a duplexer 9 for demultiplexing a transmission/reception signal of the 2 GHz band, a low noise amplifier 10 amplifying a reception signal of a 2 GHz band primary receiver circuit with a low noise, a low noise amplifier 14 amplifying a reception signal of a 2 GHz band secondary receiver circuit with a low noise, and a 2 GHz band reception filter 15 for eliminating unnecessary waves.
Further, the GPS reception system includes a low noise amplifier 16 amplifying a GPS reception signal with a low noise and a GPS reception frequency band reception filter 17 for eliminating unnecessary waves.
Furthermore, the wireless communication device of FIG. 1 is configured by a primary (main) antenna 21, a measurement use connector 22, a secondary (sub) antenna 23, an antenna switch 11 for enabling the primary (main) antenna 21 and measurement use connector 22 to be shared by both systems of the 800 MHz band and 2 GHz band, and a triplexer 18 for enabling the secondary (sub) antenna 23 to be shared by the 800 MHz band secondary receiver circuit, 2 GHz band secondary receiver circuit, and GPS receiver circuit.
FIG. 2 is a diagram showing an example of the circuit of the antenna switch 11 of FIG. 1.
The antenna switch 11 of FIG. 2 has an 800 MHz band signal use input/output terminal T1, a 2 GHz band signal use input/output terminal T2, a control signal use terminal T3, a primary (main) antenna use connection terminal T4, a connection terminal T5 with the measurement use connector 22, switches SW1 to SW8, capacitors C1 to C4, and a control circuit 11A performing on/off control of switches SW1 to SW8.
Patent Document 1: Japanese Patent Publication (A) No. 1-112382
Patent Document 2: Japanese Patent Publication (A) No. 2003-152588